Control mechanism for pumps



May 31, 1932. w, ERN$T 1,861,116

CONTROL MECHANISM FOR PUMPS 7 Filed May 2, 193 1 3 Sheets-Sheet 1 3nnentor,' wlf'vwi,

dttomcgs May 31, 1932. w. ERNST 1,861,116

CONTROL MECHANISM FOR PUMPS Filed May 2, 1951 3 Sheets-Sheet 2 Inventor, Z'IVZ 'Z',

attorneys.

l was :i l i QQIv W la/ lwxm It .Q R Q Q Q May 31, 1932. w. ERNST CONTROL MECHANTSM FOR PUMPS Filed May 2, 1931 3 Sheets-Sheet 3 Patented May 31, 1932 UNITED STATES PATENT OFFICE WALTER ERNST, OF' MOUNT GILEAD, OHIO, ASSIGNOR TO' THE HYDRAULIC I MANUFACTURING COMPANY, OF MOUNT GILEAD, OHIO common mncmmsm ron PUMPS Application med my 2,

This invention relates to control mechanism for pumps and more tparticularly to.

' disclosed in connection with a pump of the radial, reversible, variable discharge kind now well known in the art.

Pumps of this kind are exemplified by the pump disclosed in United States Letters Patent 1,250,170, granted to Hele-Shaw, et al., December 18, 1917. Briefly stated, such pumps include a plurality of radially arranged cylinders and pistons, the rate and direction of dischargeeflectedjby which depend upon the eccentricity of the cylinder and piston assembly relative to a drive shaft. The cylinders are usually carried by a floating ring or the like, which, by means o'f a' cross head or other control element, maybe" shifted to vary the eccentricity of the cylinders "and to thereby eilect control of the pump'discharge. Various other kinds of variable discharge pumps are known in'the" art', and it will be understood that the present invention relates to control mechanism .for usein connection with pumps diflering in some respects from the pump illustrated herein.

An object of the invention is to improve generally the construction and operation of control mechanism for pumps of this general character.

Another object is to pr0vide,'in such a control mechanism, adjustable means for limiting the maximum discharge pressure of the pump to any desired value. Other and more specific objects will become apparent from a reading of the following description, the

appended claims, and the several views of the;

drawings, in which:

Figure 1 is a view partly in frent elevation and partly in vertical section of a pump and control mechanism embodying the invention,

1m. serial No. 534,626.

a hydraulic circuit to which the pump is connected being shown diagrammatically;

Figure 2 is a horizontal sectional view- 'taken on the line 2-2 of Figure 1;

Figure 3 is a vertical sectional view taken on the line 33 of Figure 2; and

Figure 4 is a view partly in front elevation .being connected to a pump Aof the radial,

reversible, variabledischarge type-.In order to make the operation-of the pump and control mechanism more readily understood,

the pump is illustrated as having hydraulic I connection with a hydraulic press or the like B, it however being understood that the press and hydraulic circuit constitute no part of the present invention.

As shown,'the pump A includes a casing 1, a shaft 2 which may be driven from an suitable source ofpower, and combined Intake and discharge pipes 3 and 4. The pipe 3 is connected to the upper end of the cylinder 5 of the press B and the pipe 4 is connected to the lower end/of the cylinder. When the pump is discharging through the pipe 3, the ram 6 of the press will be moved downwardly to perform a pressing or other like operation, the pump at this time receivin its intake princi ally' from the lower en of the press cylin er. When the pump-is reversed so as to discharge in the opposite direction, that is, through the pipe 4, fluid will be drawn from the upper end of the cylinder and delivered underpressure to the lower end thereof to return the mm to its upper position. -A compensating valve 7 of the kind fully disclosed in the United States patent to Walter Ernst 1,653,350, dated December 17, 1927, is connected across the pipes 3 and4 and has its central chamber 8 connected to a tank 9 by'means of a pipe 10 for compensating for the unequal efiective cross sectional *area of the cylinder 5 above and below the piston 6 in a manner well understood in the art.

As shown in Figures 1 and 2, the pump A includes a pair of floating rings 11-11 mounted in the casing 1, these'rings being movable radially with respect to the pum shaft for varying the pump discharge. R0 1212 are connected to the rings 11-11 and extend through the casing at 13-13, the outer ends of the rods being connected by a cross head or pump control element 14 secured to the rods by nuts 1515. Rods 1616, also connected to the rings 11'11,extend'throu h the opposite side of the casing at 1717, t 1e outer ends of these rods being connected by a cross head 18 secured to the rods by nuts 19. Referring now to the control mechanism forming the subject matter of the present invention, and particularly to the embodiment illustrated in Figures 1, 2, and 3, a bracket 20 is mounted in fixed relation to the pump casin and serves to support two hydraulic cylinders 2121, one disposed above the other. The cylinders 21--21 are disposed respectively above and below the plane containing the rods 12-12 and cross head 14 and have their axes extending in the direction of movement of the rods and cross head.

For moving the cross head or control element 14 there is provided a power operated actuating device connected to the cross head through the medium of a yieldable connection adapted to be adjusted so as to determine the maximum discharge ressure of the pump. In the form shown in igures 1,2, and 3, a pair of double-acting hydraulic pistons 22-22 is rovided, one being mounted in each of the cylinders 21. Each piston is provided with a stem 23 which extends inwardly toward the pump and through packing 23a for threaded connection to a vertical cross head 24 as at 25. The cross head 24 conneccs the two stems 23 and extends vertically past the control element or cross head 14 of the pump for moving the latter in either direction in a manner to be described.

A rod'26 has its inner end connected to the cross head 24 by means of a threaded'connection 27, a flan e 28 on the rod abutting against the outer ace of the cross head. The rod extends freely through an opening 29 in the control element 14, and the latter is formed with a depression 30 for receiving the flange 28 and permitting the cross head 14 to abut against the cross head 24. The outer .end of; the rod 26 is formed with an acme thread 31, and a l and wheel 32 is rotatable upon ,the threaded portion ofthe'rod 26. A

spring33 is interposed between the hand 7 the end of the spring bears. A thrust bearing 37 is disposed between the flange 36 and the hand wheel for facilitating rotation of the latter for adjustment of the spring,-and

a nut 38 is provided at the extreme end portion of the rod 26 for preventing accidental displacement of the hand wheel from the rod.

For -moving the pistons 22 to shift the control element 14 and to vary the discharge of the pump, means are provided for applying fluid pressure to either side of the pistons. In the form shown, this pressure-applying means includes a low ressure pump 39 arranged to receive fluld' from the tank 9 through. the medium of a suction pipe 40 and to discharge fluid under a relatively low pressure through a pipe 41 to a pilot valve generally designated 42 which controls the application of pressure on the respective sides of the pistons 22 through pipes 43 and 44.

The pilot valve 42 includes a liner or sleeve 45 mounted in a bore 46 in the pump casing. This liner is provided with ports 47 47 communicating with an annular recess 48 in the casing and with ports 49-49 axially spaced from the ports 4747 and communicating with an annular recess 50. The discharge pipe 41 leading from the low pressure pipe 39 communicates with the interior of the liner 45 midway between the ports 47-47 and the ports 49-49. [Mounted in the liner 45 is a piston valve 51 having spaced heads 52 and 53 formed on a stem 54, the center-to-center distance between the heads 52 and 53 being the same as the center-to-center distance between the ports 47 and the ports 49. The heads 52 and 53 are slightly wider than the associated openings 47 and 49, so that, when the piston valve is in its Figure 1 position, the heads 52 and 53 will just cover the ports 47 and 49 respectively.

The stem 54 of the piston valve extends outwardly through packing 55 for pivotal connection with the upper end of a floating lever 56 as at 57. The float-ing lever 56 is pivotally connected at an intermediate point as at 58 to alink 59, in turn pivotally connected to the cross head 18 as at 60, and the lower end of the floating lever is' pivoted as at 61 to a link 62 which is in turn pivoted, as at 63, to the lower end of a manually operable control member or lever 64 journalled in a bracket 65 as at 66.

In operation, if the control member 64 is moved in a direction to move the piston valve 51 to the right from its Figure 1 position, low pressure fluid from the pipe 41 will enter the liner between the heads 52 and 53 and will flow out through the ports 49 and annular recess" 50, since the head 53 has been moved to the right of the ports 49. The fluid will flow from the recess 50 through the pipe 43 to the right of the pistons 22, and will move the latter to the left, fluid contained in the cylinders 21 to the left of the pistons 22being' expelled through the pipe 44, the annular recess 48, the ports 47, an internal passage 67 formed in the piston valve, a chamber 68 in the casing at the inner end of the liner 45, and an exhaust pipe 69 which leads back to the tank 9. As the pistons 22 are moved to the left in this manner, the cross head 24 and the rod 26 will be also moved to the left, thereby transmitting force through the spring 33 against the outer face of the control element or cross head 14 so as to move the latter to the left and effect discharge through-the pipe 3 of the pump. Assuming that the control member 64has moved the valve 51 to a def- 20 inite position to the right of the Figure 1 position, and the control member then set in its new position, movement of the pistons 22 and resultant movement of the pump control element 14 and the cross head 18 at the opposite side of the pump will continue until the valve 51 has been returned nearly to its Figure 1 position through the rocking of the floating lever 56 about the pivot 61 resulting from movement of the cross head 18 imparted to the floating lever through the link 59. As soon as the piston valve 51 has been moved to this position, further flow of fluid to the right hand end of the cylinders 21 will be arrested and the pistons 22, the cross head 24, and pump control element 14 will be brought to rest.

Similarly, if the control member 64 is moved to bring the piston valve 51 to a predetermined position to the left of its Figure 1 position, fluid from the discharge pipe 41 will be directed through the pipe 44 to the left hand ends of the cylinders 21 so as to' move the pistons 22 to the right, the movement of the pistons being transmitted through the cross head 24 directly to the control element 14 of the pump to effect discharge through the pipe 4 of the pump. WVhen the desired movement of the cross'head 14 to the right has taken place, the piston valve 51 will be automatically returned nearlyto its Figure 1 position so as to prevent further flow of low pressure fluid to the 'cylinders 21, thereby bringing the pump control element 14 to rest. 1 From the foregoing, it will be observed that different degrees of movement'of the controlelement 64 and the piston valve 51 will eifect correspondinglydifferent degrees of movement of the pump control element 14 so as to produce the desired direction and rate of discharge from the pump. i

When the piston valve 51' is in its Figure 1 position, wherein the ports 47-47 and the ports 49-49 are covered by theheads 52 and 1 53 respectively, fluid cannot flow through the pipe 41. In order to relieve the pressure in the pipe 41 when the valve is in this position, a relief pipe 66a, including a pressure operated relief valve 666 of any suitable form, is connected between the pipe 41 and the tank 9.

In accordance with a further feature of the invention, means are provided for limiting the maximum pressure of fluid discharged by the pump. For limiting the pressure of fluid discharged through the pipe 3, a piston 70 mounted in a cylinder '71 has a stem T2 extending through packing 73 for connection with the cross head 18 as at 74. The cylinder 71 communicates at its left hand end, as viewed in Figure 1, with the pipe 3 of the pump by means of a pipe 75, so that the pressure in the cylinder 71 and to the left of the piston 70 is always the same as the pressure in the pipe 3. Assuming that the piston valve 51 has been moved to the right, and that the pistons 22, the-cross head 24, the rod 26, and the pump control element 14 have been moved to the left to a predetermined position in the manner described above, these parts will remain in such-position until the pressure in the pipe 3 builds up toa predetermined extent, at which-time this pressure, acting through the pipe 75 and in the cylinder 71, will act upon the piston 70 to move the latter to the right, this movement being transmitted through the stem 72 and cross head 18 to the rods 16-16 and to the floating rings 1111 of the pump, thus moving thev floating rings to the right and reducing the discharge rate of the pump. The movement of the rings at this time takes place independently of any movement of the pistons 22-22, this being possible because of the compressibility of the spring 33 forming a part of the connections interposed between the control element 14' and-the pistons 22. In other words, when the pressure builds up to a predetermined extent in the pipe 3 and the cylinder 71, the. piston 70 Wil1 move the floating rings 11 and the pump control element 14 to the right against the urge of the spring,33.. By means of the hand wheel 32, the spring 33 may be initially compressed to any desired degree so as to vary the amount of pressure required in the cylinder 71 to overcome the force of the spring 33 to reduce the dis-- charge rate of the pump and to thereby limit its maximum discharge pressure. It will be apparent that the handvwheel 32 provides means for regulating the action of the pressure responsive piston 70.

It is desirable that means he also provided for limiting the maximum discharge pressure of the pump when the control element 14 and floating rings 11 have been moved to the right so as to discharge through the pipe 4 in the manner already described. For this purpose, each piston 22 is provided with a plunger 76 extending'into a bore 77 in the head of the associated cylinder, the ends of these bores communicating at all times with the pipe 4 through the medium of a pipe 78. Thus, when the pistons 22 and control element 5 14 have been moved to the right in the manner described above so as to efi'ect a predeterminedrate of discharge through the pipe 4, pressure built u to a predetermined extent in the pipe 78 an bores 77 will act upon the plunger 76 to move the latter and the istons 22 to the left. It will be understood t iat the unit pressure acting upon the relatively small area of the plunger 76 is much greater than the unit pressure acting upon the relatively 15 large area of the left hand faces of the pistons 22, so that this latter pressure is overcome by the high pressure in the bores 77, the fluid in the left of the cylinders 21 bein forced through the pipe 44 and past the va ve head 52, which permits a limited amount of leak-' age. This results in movement of the pistons 22 and cross head 24 to the left, this movement of the cross head 24 being transmitted through the rod 26, the hand wheel 32, and the spring 33 to the pum moving the latter to t e left and reducing the rate of discharge through the pipe 4 so asto limit the discharge pressure.

In order that the invention may be more readily understood in its entirety, a comlete operating cycle of the circuit shown in i ure 1 will now be described.

suming that theparts are in the relative positions shown in Figures 1 and 2,. the pump will be on neutral, that is, no fluid will be delivered throu h either of the pi es 3 and.

' 4. When it is esired to effect a ownward movement of the ram 6, the control member 64 is moved'to the right to an extent dependent upon the desired rate of discharge of the pump. This will move the piston valve 51 to the right to admit'fluid from the pipe 41 to the pipe 43 and to the right hand end of the c linders 21. The pistons 22 will be there y moved to the left, movement of the pistonsbeing transmitted to the pump control element 14 through the cross head 24, the rod 26, the handwheel 32, and the spring 33. When the control element 14 and floating rings 11 of the pump have been moved to the left to a position dependent upon the original degree ofrmovement of the control member 64, the piston valve 51 will be returned to its Figure 1 position as described above, and the control element 14 and floating ringsll will be brought to rest, after which the pump will deliver fluid through the pipe 3 at the desired rate. When the ram 6 encounters resistance to its downward movement, pressure will build up in the pipe 3, and, when this pressure has reached a value .dependent upon the initial adjustment of the spring 33 the piston will move the cross head 18, floating rin 11, and pumpcontml I element 14 to the rig t against the spring 33,

control element 14 thereb reducing the discharge rate and limiting the maximum pump pressure. In order to return the ram 6 to its upper position, the control member 64' is moved in a counterclockwise direction, thereby moving the iston valve 51 to the left and directing uid from the pipe 41 to the left hand ends of the cylinders 21, thereby moving the pistons 22, t 1

e cross head 24, and the control element 14 to the right in the manner described. If the ram 6 encounters resistance to its upward movement, pressure will build up in the bores 77 and will act upon the plunger 76 to move the pistons 22, the cross head 24, and the control element 14 toward the left to decrease the rate of discharge and limit the discharge pressure. When the upward stroke of the ram 6 has been completed, the pump control element 14 may be returned to its neutral position by operating the ilot valve 51 so as to admit just enou h uid to the right hand ends of the ,cylin ers 21 to move the pistons 22, the cross head 24, and the control member 14 to the left to their Figure 1 positions.

Although the controlling mechanism forming the subject matter of the present invention has been illustrated in connection with a pump forming part of a hydraulic circuit for operating a hydraulic press, it is to be understood that the invention is not limited to such application, and may be used wherever it is desirable to control the rate of discharge and the maximum discharge pressure of a variable discharge pump. v

In the modified form shown in Figure 4, a single piston 79 is used in place of the two pistons 2222 ofthe Figure 1 construction, the piston 79 being mounted in a cylinder 80 supported on the pump casing by means of a bracket 81. The piston 79 is directly connected to the pump control element 14 by means of astem 82 extending through packing 83, the piston 79 serving to move the control element 14 in both directions'to reverse the pump discharge and to vary the rate thereof. A plunger 83 formed on the piston extends into a bore 84 formed in the c linder head, the bore communicating with t e pipe 4 of the pump by means of the pipe 78 as in the arrangement shown-in Figure 1. This embodiment of'the invention is suitable for I use where it is not necessary to provide in the pump control mechanism itself means for varying the maximum dischar e pressure, it being noted that'the piston 79 is directly connected to the control element 14 as distinguished from being connected to the control element through the yieldable spring 33 included in the construction shown in Figure 1. The pilot valve mechanism of the Figure 4 formis the same as that shown in Figure 1 and already described in detail, so that further reference thereto will not be necessary.

It will be apparent that the control mechanism disclosed'herein may be used in connection with various kinds of pumps other than the type illustrated herein, and that various other changes may be niade without departing from the scope of the invention as defined in the claims.

I claim 1. A control mechanism for a variable discharge pump of the type including a movable pump discharge control element, said mechanism comprising in combination with said control element; a 'power operated rod extending in the direction of movement of said control element; a movable abutment on one end of the rod and being positioned on one side-0f said pump control element said control element being movable relative to said rod and abutment; a spring carried by said rod and yieldably urging said control element and abutment into engagement; and means for adjusting said spring.

2. A control mechanism for a variable discharge pump of the type including a movable pump discharge control element, said mechanism comprising in combination with said control element; an actuating rod extending in the direction of movement of said control element; a movable abutment on one end of said rod and normally engaging one face of said control element; a compression spring mounted on said rod and having one end engaging the opposite face of said movable abutment; means on the other end of the rod "or adjustably compressing said spring: and means responsive to pressure of the fluid dis-.

charged by said pump for urging said control control element; a'cylinder, a piston therein a cross head connected to said piston; a rod having its inner end connected to said cross head and extending freely through said control element; a hand wheel having threaded connection with the outer end of the rod; a compression spring interposed between said hand wheel and said control element for urging the latter against said cross head; and means for admitting fluid pressure to said cylinder for operating said piston to move said cross head and control element in one direction to effect discharge of the pump.

4. A control mechanism fora variable discharge pump of the type including amovable pump discharge control element :saidmechanism comprising in combination with said control element; a cylinder, a piston therein: a cross head connected to said piston; a rod having its inner end, connected to said cross head and extending freely through said control element; a hand wheel having threaded connection with the outer end of the rod; a. com ression spring interposed between said han wheel and said control element for urging the latter against said cross head; means for admitting fluid pressure to said cylinder for operating said piston to move said cross head and control element in one direction to effect discharge of the pump; and means connected to said control element and being responsive to pressure of fluid discharged by said pump for moving said control element in the opposite direction against the urge of said spring.

5. A control mechanism for a reversible variable discharge pump of the type including a movable pump discharge control element, said mechanism comprising in com-.

bination with said control element; a cylinder: a double-acting piston therein; a cross head connected to said piston; a rod havin its inner end connected to said cross head an extending freely through said control element; a hand wheel having threaded connection with the outer end of said rod; a compression spring interposed between said hand wheel and said control element for urging the latter against said cross head; a pilot valve for controlling application of fluid pressure to either side of said piston to -move the piston, cross head, and control element in a direction to produce discharge of the pump in the desired direction; and means responsive to pressure of thefiuid discharged by the pump for moving said control element against the urge of said spring and out of contact with said cross head to limit the maximum discharge pressure.

6. A control mechanism for a reversible variable discharge-pump of the type including a movable pump discharge control ele ment, said mechanism com rising in combination with said control e ement; a pair of cylinders fixed with respect to said pump; a double-acting piston ineach cylinder; a cross head connected to said pistons; a rod having its inner end connected to said cross head and extending freely through said control element; a hand wheel havin threaded connection with the outer end 0 said rod; a compression spring interposed between said hand wheel and said control element for urging the latter against said cross .head; a pilot valve for controlling application of fluidpressure to either side'of said pistons to move the pistons, cross head, and control element in a direction to produce discharge-of the pump in the desired direction; and means responsiye to pressure of the fluid'discharged by the pump for moving said control element against the urge of said spring and out of contact with said cross head to limit the maximum discharge pressure.

7. A control mechanism for a variable discharge pump of the type including a movable pump discharge control element, said mechanism comprising in combination with said control element; a fluid actuated piston for moving said control element in ,one direction; a yieldable connection between said piston and said control element: means responsive to pressure of the fluid discharged by said pump for urging said control element in the opposite direction independently of movement of said piston; means for adjusting said ieldable connection to fix the pressure at w ich said pressure responsive means will become active; and a pilot valve for controlling application of fluid pressure to said piston, said valve being operatively connected to said control element whereby different degrees of movement of said valve will produce correspondingly different degrees of movement of said piston and pump control elements.

8. A control mechanism for a reversible variable discharge pump of the type including a movable ump discharge control element, said mec anism comprising in combination with said control element; a cylinder; a double acting piston therein; a-cross head-connected to said piston; a rod having its inner end connected to said cross head an d extending freely throu h said control element; a hand wheel having threaded connection with the outer end of said rod; :1 compression spring interposed between said and wheel and said control element for urging the latter against said cross head; a

i t valve for controlling application of uid pressure to either side of said piston to move the piston, cross head, and control element in a direction to produce discharge of the pump in the desired direction; pressure responsive means connected to said pump control element and operable upon building upl of a predetermined discharge pressure w on the pump is discharging in one direction and independently of movement of said piston to move said ump control element against the urge of said spring to reduce the rate of pump discharge; and pressure re- 'sponsive means connected to said piston and operable upon building up of a predetermined discharge pressure when the pump is discharging in'the other direction to move said piston, cross head, and pump control element to reduce the rate of pump discharge.

9. A control mechanism for a reversible variable discharge pump of the type including a movable pump discharge control element, said mechanism comprising in combination with said control element; a cylinder; "a double-acting piston therein; a cross head connected to said piston: a rod havin its inner end connected'to said cross headan extendin freely through said control element; a ban wheel having threaded connection with the outer end of said rod; a compression spring interposed between said hand wheel and said control element for urging the latter against said cross head; a pilot valve for con trolling application of fluid pressure to either side of said piston to move the piston, cross head, and control element in a direction to produce discharge of the pump in the desired direction; pressure responsive means connected to said pump control element and operable upon building up of a predetermined discharge pressure when the pump is discharging in one direction and independently of movement of said piston to move said pump control element against the urge of said spring to reduce the rate of pump dis: charge; pressure responsive means connected to said piston and operable upon building up of a predetermined discharge pressure when the pump is discharging in the other direction to.move said piston, cross head, and pump control element to reduce the rate of pump discharge, said valve being operative- 1y connected to said control element whereby different degrees of movement of said valve will produce different degrees of movement of said piston and pump control element.

10. A control mechanism for a reversible variable discharge pump of the type including a movable pump discharge control element, said mechanism comprising in combination with said control element; a doubleacting fluid actuated piston connected to said pump control element for moving the latter in either of two directions to efiect varied rates of discharge in either direction; a pilot valve for controlling a plication of fluid pressure to said piston; a floating lever pivotally connected at an intermediate point to said pump control element and pivotally connected at one of its ends to said pilot.

valve; and a control member connected to the opposite end of said floating lever.

11. A control mechanism for a reversible variable discharge pump of the type including a movable ump discharge control element, said mec anism comprising in combi nation with said control element; a doubleacting fluid actuated piston connected to said pump control element for moving the latter in either of two directions to efl'ect varied pump ischarge control element, said mechanism comprising in combination with said uid discharged by control element; a spring connected to said control element; a fluid" actuated piston connected to said spring for transmitting force through the latter tomove said pump control element to effect a desired rate of discharge of said pump; a pilot valve for controlling application of fluid pressure to said piston; a floating lever pivotally connected at an intermediate point to said pump control element-and pivotally connected at one I of its ends to said pilot valve; a control member connected to the opposite end of said floating lever; means res onsive to pressure of fluid discharged by sai pump for moving said control element in a direction opposite to the force exertedby said spring to reduce the rate of pump discharge; and means for adjusting said spring to determine the pressure required to operate said pressure responsive means.

In testimony whereof, I have hereunto subscribed my name. p

. WALTER ERNST. 

